Results 41 to 50 of about 909 (203)
CCD astrometry of faint compact extragalactic radio sources. III. [PDF]
Astronomy & Astrophysics, 2001 Optical positions relative to the Hipparcos Catalogue (ESA 1997) have been obtained for the optical counterparts of 28 faint (B 20 23) southern compact extragalactic radio sources (CERS). Most of these sources are not adequately observable (or simply not visible) by means of direct photography with a conventional wide- eld telescope, so the positions ...
E. Costa, P. Loyola
openaire +6 more sources
VERA’s 20 yr Evolution in Science and Technology
GalaxiesWe review the past 20 yr evolution of VERA (VLBI Exploration of Radio Astrometry) in both science and techinology. VERA is a VLBI array in Japan which consists of four 20 m-diameter telescopes, originally dedicated to phase-referencing VLBI astrometry ...
Mareki Honma +3 more
doaj +1 more source
The VERA project (VLBI Exploration of Radio Astrometry) [PDF]
Proceedings of the International Astronomical Union, 2004 VLBI – Very Long Baseline Interferometry – is a radio interferometry technique which provides the highest spatial resolution observations to human kind. But at the present, the accuracy of the astrometry observations is limited by the atmospheric light path variations and instrumental phase errors, and only group delay measurements are used.
Hideyuki Kobayashi +9 more
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Nanoradian Ground-Based Astrometry, Optical Navigation, and Artificial Reference Stars
, 2016 Spacecraft carrying optical communication lasers can be treated as artificial stars, whose relative astrometry to Gaia reference stars provides spacecraft positions in the plane-of-sky for optical navigation.
Biswas, Abhijit +12 more
core +2 more sources
Modern astrometry in different ranges of electromagnetic waves
, 2005 A contribution of various astrometry school beginning from the German school after F. Bessel is described. Besides, the modern astrometry problems and prospects connected with the further increasing of the accuracy and with developing of a single ...
Kharin, A.S.
core +2 more sources
The jet of the Low Luminosity AGN of M81
EPJ Web of Conferences, 2013 In this contribution, we summarize our main results of a big campaign of global VLBI observations of the AGN in M81 (M81*) phase-referenced to the radio supernova SN 1993J.
Alberdi A. +6 more
doaj +1 more source
An Updated Reference Frame for the Galactic Inner Parsec
The Astrophysical Journal, 2023 Infrared observations of stellar orbits about Sgr A* probe the mass distribution in the inner parsec of the Galaxy and provide definitive evidence for the existence of a massive black hole.
Jeremy Darling +5 more
doaj +1 more source
Advances in Astronomy, Volume 2026, Issue 1, 2026.The continued detection of near‐Earth asteroids with postulated close encounters with Earth is a clear motivation for planetary defense–driven mission designs. Fast reconnaissance in an imminent threat scenario (i.e., less than a few years upon impact) is crucial to gain information about an asteroid potentially impacting the Earth in the near future ...
Markus Patzek +11 more
wiley +1 more source
The Astrophysical Journal, 2023 We have observed the low-mass protostellar source IRAS 15398−3359 at a resolution of 0.″2–0.″3, as part of the Atacama Large Millimeter/Submillimeter Array Large Program FAUST, to examine the presence of a hot corino in the vicinity of the protostar.
Yuki Okoda +18 more
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Advances in Astronomy, Volume 2026, Issue 1, 2026.This paper investigates the degradation of pointing accuracy in the Kunming 40‐m radio telescope due to long‐term equipment aging and environmental disturbances. Conventional linear pointing models are constrained by their linear modeling framework, making it difficult to accurately represent the nonlinear errors induced by temperature, wind speed, and
Yao He +3 more
wiley +1 more source